Incoming Log for Linksys Router

[Steve-O]

I have a DSL Modem feeding a Linksys DSL Router BEFSR41 with a 4 port switch. I turned on incoming log, not fully understanding its import. Each day it seems to double in size. Sometimes I'm able to resolve an IP to an address using the ping command parameter, and sometimes it gives me a domain name, sometimes not. Could someone help me understand the significance of the incoming log and how to clear/reset it? I'm new to DSL and networking, so please be gentle :p Thanks in advance for your assistance.